If it has chess, it has combinatorics
Source: OMEC Ecuador National Olympiad Final Round 2021 N3 P4 day 2
November 7, 2024
combinatoricsnational olympiad
Problem Statement
In a board x, the unit squares have numbers , as shown. The unit square with a multiple of on it are red. Find the minimum number of chess' bishops that we need to put on the board such that any red unit square either has a bishop on it or is attacked by at least one bishop.
Note: A bishops moves diagonally.
https://i.imgur.com/03baBwp.jpeg